var WebRtcStreamer = (function () {
  /**
   * Interface with WebRTC-streamer API
   * @constructor
   * @param {string} videoElement - id of the video element tag
   * @param {string} srvurl -  url of webrtc-streamer (default is current location)
   */
  var WebRtcStreamer = function WebRtcStreamer(videoElement, srvurl) {
    if (typeof videoElement === 'string') {
      this.videoElement = document.getElementById(videoElement)
    } else {
      this.videoElement = videoElement
    }
    this.srvurl = srvurl || location.protocol + '//' + window.location.hostname + ':' + window.location.port
    this.pc = null

    this.mediaConstraints = { offerToReceiveAudio: true, offerToReceiveVideo: true }

    this.iceServers = null
    this.earlyCandidates = []
  }

  WebRtcStreamer.prototype._handleHttpErrors = function (response) {
    if (!response.ok) {
      throw Error(response.statusText)
    }
    return response
  }

  /**
   * Connect a WebRTC Stream to videoElement
   * @param {string} videourl - id of WebRTC video stream
   * @param {string} audiourl - id of WebRTC audio stream
   * @param {string} options  -  options of WebRTC call
   * @param {string} stream   -  local stream to send
   * @param {string} prefmime -  prefered mime
   */
  WebRtcStreamer.prototype.connect = function (videourl, audiourl, options, localstream, prefmime) {
    this.disconnect()

    // getIceServers is not already received
    if (!this.iceServers) {
      console.log('rtc 服务准备完毕')

      fetch(this.srvurl + '/api/getIceServers')
        .then(this._handleHttpErrors)
        .then((response) => response.json())
        .then((response) => {
          this.onReceiveGetIceServers(response, videourl, audiourl, options, localstream, prefmime)
        })
        .catch((error) => this.onError('getIceServers ' + error))
    } else {
      this.onReceiveGetIceServers(this.iceServers, videourl, audiourl, options, localstream, prefmime)
    }
  }

  /**
   * Disconnect a WebRTC Stream and clear videoElement source
   */
  WebRtcStreamer.prototype.disconnect = function () {
    if (this.videoElement?.srcObject) {
      this.videoElement.srcObject.getTracks().forEach((track) => {
        track.stop()
        this.videoElement.srcObject.removeTrack(track)
      })
    }
    if (this.pc) {
      fetch(this.srvurl + '/api/hangup?peerid=' + this.pc.peerid)
        .then(this._handleHttpErrors)
        .catch((error) => this.onError('hangup ' + error))

      try {
        this.pc.close()
      } catch (e) {
        console.log('Failure close peer connection:' + e)
      }
      this.pc = null
    }
  }

  /*
   * GetIceServers callback
   */
  WebRtcStreamer.prototype.onReceiveGetIceServers = function (iceServers, videourl, audiourl, options, stream, prefmime) {
    this.iceServers = iceServers
    this.pcConfig = iceServers || { iceServers: [] }
    try {
      this.createPeerConnection()

      var callurl = this.srvurl + '/api/call?peerid=' + this.pc.peerid + '&url=' + encodeURIComponent(videourl)
      if (audiourl) {
        callurl += '&audiourl=' + encodeURIComponent(audiourl)
      }
      if (options) {
        callurl += '&options=' + encodeURIComponent(options)
      }

      if (stream) {
        this.pc.addStream(stream)
      }

      // clear early candidates
      this.earlyCandidates.length = 0

      // create Offer
      this.pc.createOffer(this.mediaConstraints).then(
        (sessionDescription) => {
          // console.log("Create offer:" + JSON.stringify(sessionDescription));

          // console.log(`video codecs:${Array.from(new Set(RTCRtpReceiver.getCapabilities('video')?.codecs?.map((codec) => codec.mimeType)))}`)
          // console.log(`audio codecs:${Array.from(new Set(RTCRtpReceiver.getCapabilities('audio')?.codecs?.map((codec) => codec.mimeType)))}`)

          if (prefmime != undefined) {
            //set prefered codec
            const [prefkind] = prefmime.split('/')
            const codecs = RTCRtpReceiver.getCapabilities(prefkind).codecs
            const preferedCodecs = codecs.filter((codec) => codec.mimeType === prefmime)

            // console.log(`preferedCodecs:${JSON.stringify(preferedCodecs)}`)
            this.pc
              .getTransceivers()
              .filter((transceiver) => transceiver.receiver.track.kind === prefkind)
              .forEach((tcvr) => {
                if (tcvr.setCodecPreferences != undefined) {
                  tcvr.setCodecPreferences(preferedCodecs)
                }
              })
          }

          this.pc.setLocalDescription(sessionDescription).then(
            () => {
              fetch(callurl, { method: 'POST', body: JSON.stringify(sessionDescription) })
                .then(this._handleHttpErrors)
                .then((response) => response.json())
                .catch((error) => this.onError('call ' + error))
                .then((response) => this.onReceiveCall(response))
                .catch((error) => this.onError('call ' + error))
            },
            (error) => {
              console.log('setLocalDescription error:' + JSON.stringify(error))
            }
          )
        },
        (error) => {
          alert('Create offer error:' + JSON.stringify(error))
        }
      )
    } catch (e) {
      this.disconnect()
      alert('connect error: ' + e)
    }
  }

  WebRtcStreamer.prototype.getIceCandidate = function () {
    fetch(this.srvurl + '/api/getIceCandidate?peerid=' + this.pc.peerid)
      .then(this._handleHttpErrors)
      .then((response) => response.json())
      .then((response) => this.onReceiveCandidate(response))
      .catch((error) => this.onError('getIceCandidate ' + error))
  }

  /*
   * create RTCPeerConnection
   */
  WebRtcStreamer.prototype.createPeerConnection = function () {
    // console.log('createPeerConnection  config: ' + JSON.stringify(this.pcConfig))
    this.pc = new RTCPeerConnection(this.pcConfig)
    var pc = this.pc
    pc.peerid = Math.random()

    pc.onicecandidate = (evt) => this.onIceCandidate(evt)
    pc.onaddstream = (evt) => this.onAddStream(evt)
    pc.oniceconnectionstatechange = (evt) => {
      // console.log('oniceconnectionstatechange  state: ' + pc.iceConnectionState)
      if (this.videoElement) {
        if (pc.iceConnectionState === 'connected') {
          this.videoElement.style.opacity = '1.0'
        } else if (pc.iceConnectionState === 'disconnected') {
          this.videoElement.style.opacity = '0.25'
        } else if (pc.iceConnectionState === 'failed' || pc.iceConnectionState === 'closed') {
          this.videoElement.style.opacity = '0.5'
        } else if (pc.iceConnectionState === 'new') {
          this.getIceCandidate()
        }
      }
    }
    pc.ondatachannel = function (evt) {
      // console.log('remote datachannel created:' + JSON.stringify(evt))

      evt.channel.onopen = function () {
        // console.log('remote datachannel open')
        this.send('remote channel openned')
      }
      evt.channel.onmessage = function (event) {
        // console.log('remote datachannel recv:' + JSON.stringify(event.data))
      }
    }

    try {
      var dataChannel = pc.createDataChannel('ClientDataChannel')
      dataChannel.onopen = function () {
        // console.log('local datachannel open')
        this.send('local channel openned')
      }
      dataChannel.onmessage = function (evt) {
        // console.log('local datachannel recv:' + JSON.stringify(evt.data))
      }
    } catch (e) {
      console.log('Cannor create datachannel error: ' + e)
    }

    // console.log('Created RTCPeerConnnection with config: ' + JSON.stringify(this.pcConfig))
    return pc
  }

  /*
   * RTCPeerConnection IceCandidate callback
   */
  WebRtcStreamer.prototype.onIceCandidate = function (event) {
    if (event.candidate) {
      if (this.pc.currentRemoteDescription) {
        this.addIceCandidate(this.pc.peerid, event.candidate)
      } else {
        this.earlyCandidates.push(event.candidate)
      }
    } else {
      // console.log('End of candidates.')
    }
  }

  WebRtcStreamer.prototype.addIceCandidate = function (peerid, candidate) {
    fetch(this.srvurl + '/api/addIceCandidate?peerid=' + peerid, { method: 'POST', body: JSON.stringify(candidate) })
      .then(this._handleHttpErrors)
      .then((response) => response.json())
      .then((response) => {
        // console.log('addIceCandidate ok:' + response)
      })
      .catch((error) => this.onError('addIceCandidate ' + error))
  }

  /*
   * RTCPeerConnection AddTrack callback
   */
  WebRtcStreamer.prototype.onAddStream = function (event) {
    // console.log('Remote track added:' + JSON.stringify(event))

    this.videoElement.srcObject = event.stream
    var promise = this.videoElement.play()
    if (promise !== undefined) {
      promise.catch((error) => {
        // console.warn('error:' + error)
        this.videoElement.setAttribute('controls', true)
      })
    }
  }

  /*
   * AJAX /call callback
   */
  WebRtcStreamer.prototype.onReceiveCall = function (dataJson) {
    // console.log('offer: ' + JSON.stringify(dataJson))
    var descr = new RTCSessionDescription(dataJson)
    this.pc.setRemoteDescription(descr).then(
      () => {
        // console.log('setRemoteDescription ok')
        while (this.earlyCandidates.length) {
          var candidate = this.earlyCandidates.shift()
          this.addIceCandidate(this.pc.peerid, candidate)
        }

        this.getIceCandidate()
      },
      (error) => {
        console.log('setRemoteDescription error:' + JSON.stringify(error))
      }
    )
  }

  /*
   * AJAX /getIceCandidate callback
   */
  WebRtcStreamer.prototype.onReceiveCandidate = function (dataJson) {
    // console.log('candidate: ' + JSON.stringify(dataJson))
    if (dataJson) {
      for (var i = 0; i < dataJson.length; i++) {
        var candidate = new RTCIceCandidate(dataJson[i])

        // console.log('Adding ICE candidate :' + JSON.stringify(candidate))
        this.pc.addIceCandidate(candidate).then(
          () => {
            // console.log('addIceCandidate OK')
          },
          (error) => {
            console.log('addIceCandidate error:' + JSON.stringify(error))
          }
        )
      }
      this.pc.addIceCandidate()
    }
  }

  /*
   * AJAX callback for Error
   */
  WebRtcStreamer.prototype.onError = function (status) {
    // console.log('onError:' + status)
  }

  return WebRtcStreamer
})()

if (typeof window !== 'undefined' && typeof window.document !== 'undefined') {
  window.WebRtcStreamer = WebRtcStreamer
}
if (typeof module !== 'undefined' && typeof module.exports !== 'undefined') {
  module.exports = WebRtcStreamer
}
